feat: add the official Nextflow Language Server nextflow_ls (#3423)

* feat: add nextflow_ls

lua/lspconfig/configs/nextflow_ls.lua

@@ -0,0 +1,43 @@
+local util = require 'lspconfig.util'
+
+return {
+  default_config = {
+    cmd = { 'java', '-jar', 'nextflow-language-server-all.jar' },
+    filetypes = { 'nextflow' },
+    root_dir = util.root_pattern('nextflow.config', '.git'),
+    settings = {
+      nextflow = {
+        files = {
+          exclude = { '.git', '.nf-test', 'work' },
+        },
+      },
+    },
+  },
+  docs = {
+    description = [[
+https://github.com/nextflow-io/language-server
+
+Requirements:
+ - Java 17+
+
+`nextflow_ls` can be installed by following the instructions [here](https://github.com/nextflow-io/language-server#development).
+
+If you have installed nextflow language server, you can set the `cmd` custom path as follow:
+
+```lua
+require'lspconfig'.nextflow_ls.setup{
+    cmd = { 'java', '-jar', 'nextflow-language-server-all.jar' },
+    filetypes = { 'nextflow' },
+    root_dir = util.root_pattern('nextflow.config', '.git'),
+    settings = {
+      nextflow = {
+        files = {
+          exclude = { '.git', '.nf-test', 'work' },
+        },
+      },
+    },
+}
+```
+]],
+  },
+}